Dowel means for roadway joints



4 /||i llll i v 1' a. v lull u 'lily 6 /6 J76 I July 4, 1939. J. M.OATES ,1 4,

v DOWEL MEANS FOR ROADWAY JOINTS Filed Feb. 23, 1938 2 Sheets-Shee t lJuly 4, 1939. .1. M. DATES DOWEL IEANS FOR ROADWAY JOINI'S Filed Feb.2:15,- 1938 2 Shets-$heet2 7 o o O [V Mr 2 "w w Patented July 4, 1939UNITED STATES This invention relates to roadway joints and moreparticularly to a novel dowel construction for effectively connectingadjacentslabs of a concrete roadway, particularly at the location of theex- A pansion or contraction joints.

According to the prevailing practice it is cus-, tomary to provide dowelbars embedded in the road slabs in such a way as to prevent the heavingor lifting of one slab of the roadway relative to the other, either fromextreme temperature variations, or under heavy rollingloads, or fromchanging sub-grade conditions. In many cases the accepted practice is toprovide round dowel bars of approximately three-fourths inch in diameterand approximately twenty-four inches long usually located on twelve inchcenters across the roadway, with one end of the dowels bonded into oneofthe concrete slabs while the opposite end, extending through the joint,is provided with a tubular sleeve oris coated with bituminous or othermaterial to prevent bonding of the concrete thereto so that 1 movementof the dowel in one of the slabs is permitted as a consequence ofexpansion and contraction of the slab under extreme temperatureconditions. The practice set forth as to the diameter, length andspacing of the dowels is generally recognized as being the minimum whichwill provide a sumcient area of metal to obtain the desired reinforcingefiect, having due regard tocost, but, as will be readily appreciatedbars of greater area may be used. When joints ,are prepared at thefactory to i receive dowels proper lateral spacing thereof may berendered mathematically accurate, but even many cases, if a workmanshould inadvertently step on one or more of the supports the dowelbecomes cocked and the joint is likely to be canted or tilted whichmeans either additional time inj Pia-Em OFFICE I am M. Oates, 'Ashland,Ya. Application February 2:, 1938, Serial No. 192,14:

JOINTS ,RE|S SuEsicl. 94-18) I I arelatively fixed tonnage orfabricating cost any improvement which will give better strength andbetter results with lighter or less material is an extremely importantfactor in roadway construction. 5

Having in view the foregoing general considerations the presentinvention has primarily in view a novel construction which effectseconomy in time and labor and at the same time provides a lightconstruction which gives greater strength and better results thanheavier constructions within a competitive range, while also affording:more adequate support for the dowels and joints to insure againstaccidental displacement. These important factors center about a. noveldowel which provides greater resistance to shearing v stresses betweenthe roadway slabs, and provides greater bearing area, while at the sametime utilizing less material and permitting of assembling a series ofdowels. in such away that they may be readily adapted to the particularjoint material so as in effect to provide a complete unit whose partsmay be prefabricated in the shop according to precision standards, andlater accurately assembled to be laid across the roadway at the proper25 place by unskilled labor. In that connection, the inventioncontemplates a structure which is so constructed as to be properlybraced and thus selfsustaining with the joint material with the leastpossible number of anchoring stakes or other de- 30 vices while at thesame time all of the structure involved remains in the concrete to giveadded strength and reinforcement to the slabs where it is most needed. i

Another and mor' specific object of, the inven- 35 tion is to provide anovel dowel which in its general'sense may be described as being ofU-shaped" 1 formation, the-said dowel being formed of stock ifcomparativelysmall diameter'or cross sectional area, and which becauseof its particular shape and disposition or mounting in the slabs provdes a definitely-greater percentage of shear strength and bearing areathan a straight dowel bar of larger diameter and cross sectional area.As a consequence of the disposition and use of the 4:, dowel proposedherein it is also possible to use a fewer number of dowel elementsacross the roadway. That is to say, instead of having the dowelspositioned on twelve inch centers, as in the-case of straight rounddowels, it is entirely possible to 50 place dowels of the presentconstruction-on approximately sixteen lnch. centers thus reducing thenumber of dowels to each expansion joint.

A further object of the invention isto provide novel supporting meansfor the dowels so that.

they may be properly assembled in the factory or shop and which willretain them in the desired position and arrangement until installationis complete.

With the above and other objects in view which will more readily appearas the nature or the invention is better understood the same consists inthe novel construction, combination and arrangement of parts hereinaftermore fully described, illustrated and claimed.

A preferred and practical embodiment of the invention is shown in theaccompanying drawings in which:

Figure 1 is a perspective view of a roadway joint embodying the improveddowel means.

Figure 2 is a vertical sectionalview through a completed roadway jointshowing the manner in which the dowels may be embedded in the slabs.

Figure 3 is a perspective view of the complemental dowel-chair unitsprior to assembly with the joint material.

Figure 4 is a perspective view illustrating a modified arrangement ofthe dowel units showing that they may be disposed horizontally insteadof vertically in the roadway.

Figure 5 is an enlarged perspective view of a portion of one of thedowel units shown in Figure 4.

Figure 6 is a vertical sectional view of a completed joint embodying thedowel means arranged as in Figure 4.

Similar reference characters designate corresponding parts throughoutthe several figures of the drawings.

In its general aspect the present invention includes, in combination, asuitable expansion or contraction joint or joint material designatedgenerally as A, the novel dowel units B, and their sub-grade supportingmeans designated generally as C, all of which constitute acomplete'assembly adapted to be placed across the roadway, at the jointlocation, for embedment in adjacent slabs. 1

The distinctive feature of the invention resides in the dowel bars Bwhich, as previously indi cated, are of substantially U-shapedformation, This description is intended to refer to any type of dowelwhich is formed to provide a plurality of members or arms I and2\connected by a relatively transverse member 3 or its equivalent, thearms I and 2 being preferably of the same length, or 'at least of such alength as to pass or extend through the joint A whereby the dowel may beembedded in the opposite road slabs S and SI as shown in Figure 2. 7

Referring more particularly to the dowel units B, it'may be pointed outthat the same are preferably formed of round stock of approximatelyfive-eighths of an inch in diameter and approximately twenty-one inchesin length with a total weight of 1.825 pounds whereas it is customary touse straight dowels of three-fourths inch in diameter and twenty-fourinches 'in length, with a weight of three pounds. In any event, thediameter of the stock from which the dowels are made can be considerablyless than the stock of which a single straight dowel is made. Inaddition, the total length of the dowel including the arms and legs Iand 2 andthe connecting portion 3 may be substantially the same lengthor of less length than the length of the ordinary straight dowel.However, when a dowel of smaller diameter than a straight dowel isformed in the manner proposed herein the relative length of embedment ofthe dowel in opposite I and 2 of the dowels.

slabs is considerably less than the length of embedment of a straightround or equivalent dowel for the reason that the distribution of thedowel arms in the slabs provides a more satisfactory distribution ofreinforcing material which will give up to approximately 38% greatershearing strength and 66% greater bearing area with 39% less' weight,than a straight dowel of larger diameter. In other words, it will beapparent that even though the dowel stock is smaller in diameter and ofless weight than that of a given single straight dowel, because two armsor legs of the dowel are embedded in the concrete, the totalcross-sectional area of both legs or arms is greater than a singlestraight dowel of greater diameter and hence greater sectional andbearing area is provided with less material.

In use, the adjacent dowel units B are assembled on opposite supports orchairs C so that their transverse portions 3 are arranged in staggeredrelation throughout the length of the joint. In other words, therelative position of adjacent dowels is reversed, and the transverseportion 3 of one dowel is firmly anchored in one slab while thetransverse portion of the adjacent dowel is firmly anchored in theopposite slab.

In all cases the arms or members I and 2 of the dowel are free to moverelative to the slab in which they are embedded. This is accomplished bycoating the free ends of the arms with suitable bituminous or othermaterial to prevent bonding of the concrete thereto, and by usingtubular sleeves or boots which surround the free ends of the dowel armsI and 2 and provide a definite pocket in which the free ends of thedowels may move. Accordingly, as will be observed from the drawings thefree ends of the dowelsare fitted with the tubular metallic orequivalent sleeves 4 which may be closed at one end, by pinching, toinsure that none of the plastic concrete will enter the end of the tubeopposite that telescopically fitting over the ends of the arms I and 2.

In practice, the sleeves 4 are not permanently tied or connected in anyway to the supports or chairs C but are loosely fitted to the legs orarms However, the dowels themselves are definitely and accuratelyconnected and spaced laterally and vertically by the elements which formthe chair means C prior to assembly with the joint A. That is to say,the portions of the dowel units B approaching their closed ends aresupported by tie-elements in the form of spaced rods 5 and 6 eachprovided with the upwardly converging arm portions 5a and 6a which arepreferably slightly depressed to form seats I for receiving the bottomarm of the dowel to permit of being welded thereto as indicated at W. Inaddition, the chair means C preferably includes the upper tie rod 8which lies substantially in the same vertical plane as the lower tie rod5 and is welded as indicated at W to the tops of the upper arms of thedowel units. The supporting means or chairs as above described are, ofcourse, common to opposite sides of the joint unit because the adjacentdowels are reversed as to position. The rods 5, 6 and 8 are preferablyof relatively small diameter, for example, five-sixteenths of an inchand are, therefore, comparatively light but contribute generally to thescheme of producing a light but strong joint construction while holdingthe dowels in horizontal and vertical alinement.

As will be apparent from Figure 3 alternate dowels may be assembled witha supporting chair C in such a wayas to pass through the joint A fromopposite sides, assuming that the joint has been previously providedwith suitable openings toadmit the arms I and 2 of the dowel. When theconstruction is assembled as shown in Figure 1 it may be laid across theroadway as a complete unit, and it will of course be understood that thedowel is interlocked with the joint so that it cannot twist or rockaxially, but the supports or chairs perform the important function ofinsuring that the dowels do not tilt vertically or shift laterallyendwise relative to the joint A. It will also be apparent that inassembling the dowels to the joint, the rods and 8 in each case parallelthe joint and act as stops or abutments to limit movement of the dowelstoward the joint.

The foregoing description is generic to all forms of the invention.However, it will be apparent from an inspection of Figures 1-3, inelusive, that the one way of mounting the dowel units B is to arrangethem vertically of the road slab so that the arm I is nearest thesurface of the slab while the arm 2 is positioned near the bottom.However, Figures 4-6, inclusive, of the drawings illustrate theapplication of the invention wherein the dowel units are positionedhorizontally. In this case, however, the said dowel units have the samefeatures and characteristics set forth in connection with the dowelsshown in Figures 1-3, inclusive.

As will be observed from Figures 4-6, inclusive, the dowel units B arearranged in alternately, staggered relation, the same as in Figure 1,but, due to the fact that the units are horizontally arranged, the chairmeans C is modified to the extent that the seating portion 1a of therods 5 and 6 is made longer to accommodate and support both arms of theunit instead of one arm as in the construction shown in Figures l3. Thechair means C 'in Figure 4 contains the same essential tie rods as shownin Figure 1, and the top tie rod 8 in the construction of Figures 4-6has a welded connection W2 with one or both of the legs I and 2 of thedowel units.

While, in the illustrations, the dowels are shown as being arranged inalternately staggered relation, nevertheless, it is within the scope ofthe invention to arrange all of the dowels so thattheir closed ends arelocated at the same side of the joint,and likewise all of the free endswill be arranged at the opposite side of the joint.

From the foregoing it will be apparent that the fundamentalfeature ofthe invention resides in providing a novel multi-arm or double prongmembers I and 2 of each unit B are spaced closer together than the unitsB themselves. And, because of the greater shearing strength provided itwill be possible to use a fewer number of dowel units which efiectsadded economy.

Moreover, the adjacent ends of the slab will be more eifectively heldagainst, movement 50 that relative movement between the dowel and thematerial of the slab itself is prevented with the consequence thatbreaking down of the concrete material at the dowel locations isavoided.

I claim 1. Means for connecting the slabs of roadways at joint locationsincluding a double arm dowel both arms of which pierce the jointmaterial and span the joint, and a plurality of tie members crossingsaid dowel at points spaced lengthwise thereof and supporting the dowelon the sub-grade.

2. A dowel construction for roadway joints comprising spaced two-armdowel members both arms of. which pierce the joint material and span thejoint, and means for supporting said members in rigid relation invertical and transverse planes, said means comprising continuous membersarranged substantially at right angles to and spaced lengthwise of thedowel and formed to provide lower portions engaging the sub-grade andupper portions having the dowel members secured thereto. 3. Means forconnecting roadway slabs at joint locations including units eachcomprising a pair of dowel members arranged in spaced horizontalrelation in the material forming the joint, the space between themembers being less than the space between the units, and spaced tieelements for non-tiltingly supporting said members on the sub-grade.

4. Means for connecting roadway slabs at joint locations including unitseach comprising a body having integral dowel members arranged in spacedhorizontal relation in the material forming the joint, the space betweenthe members being less than the space between the units, and means forsupporting the said members on the sub-grade including tie elementsspaced longitudinally of the members and secured thereto, said tieelements having downwardly extending sub-gradeengaging portions.

5. A dowel construction for roadway joints comprising a plurality of'road slab interlocking units each comprising a dowel of U-shapedformation presenting free and closed ends, adjacent units having thefree ends of the dowels passing through the joint from opposite sidesthereof, and means for supporting said units against horizontal orvertical displacement, said means including spaced tie rods havingportions resting on the sub-grade and other portions'connected to thearms of the dowels at the side of the joint where said closed ends ofthe dowels are located.

6. A dowel construction for roadway joints comprising, a plurality ofroad slab interengaging units each comprising a dowel of U-shapedformation having arms whose free ends pass through the joint fromopposite sides thereof, and means for supporting the dowels at oppositesides of the joint, said means at each side comprising spaced continuousrods having lower portions adapted to rest on the sub-gradeand' upperportions engaging the dowels andwelded thereto, and a rod connectingalternate dowels at the same side of the joint. t

JAMES M. OATES.

